Technical Abstract:
Dwarf fruit trees offer many advantages to fruit growers. Dwarf trees have been available to the apple industry for more than a half-century and dwarf cherry trees are now being commercially planted. Dwarf peach and pear are known, but commercial application has not yet been fully achieved with these tree fruits. In this article, genetic and horticultural practices to oproduce dwarf or small stature trees are reviewed with emphasis on the physiology of the dwarfing mechanisms. Rootstocks have been the most common method to induce dwarfing in scion cultivars, but the mechanism(s) for dwarfing by rootstocks is not well understood. Research suggests that plant hormones play a vital role in the dwarfing process regardless of the method (rootstock, root restriction, pruning, scoring, tree training, cropping, or externally applied plant growth regulators) used to dwarf a tree. Translocation and accumulation of natural auxins, gibberellins, and cytokinins have all been implicated in the dwarfing process. The possible role of these plant hormones in dwarfing is discussed in lay terms.